Monks' Secret: Asbestos Lurking Beneath Byzantine Wall Paintings

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Hundreds of years before asbestos became ubiquitous in the
construction industry, Byzantine monks used the fibrous material
in plaster coatings underlying their wall paintings during the
late 1100s, new research shows.

Asbestos is a type of natural, rock-forming mineral known for its
ability to separate into long, flexible fibers. It has long been
thought that asbestos fibers, which are corrosion- and
combustion-resistant, were first integrated into such things as
plaster, finish coatings and floors after the Industrial
Revolution.

But while investigating the 12th-century paintings in the
Byzantine monastery Enkleistra of St. Neophytos in Cyprus,
UCLA researchers discovered the magnesium silicate mineral,
chrysotile (white asbestos), in the finish coating of the plaster
underneath a portion of a wall painting. The chrysotile provided
a smooth layer with a mirrorlike surface for the painting.
[ See
Photos of the Byzantine Monastery and 12th-Century Paintings ]

"[The monks] probably wanted to give more shine and different
properties to this layer," said UCLA archaeological scientist
Ioanna Kakoulli, lead author of the new study, published online
last month in the
Journal of Archaeological Science. "It definitely wasn't a
casual decision — they must have understood the properties of the
material."

A long history of use

Though all six asbestos minerals are now
known to be carcinogenic, people have taken advantage of the
fibrous materials' unique properties for millennia. About 4,500
years ago, artisans mixed asbestos minerals with clay to produce
stronger pottery. And 2,000 years ago, asbestos fibers were woven
into textiles to make fireproof napkins (that were "washed" by
tossing them into fire), or to make a special fabric that could
separate human ashes from funeral pyre material during
cremations, Kakoulli said. "It was considered to have magical
powers," she told Live Science.

In the late 19th century, people used asbestos in industrial
products — including cements, wall plasters, joint (drywall)
compounds, fire-retardant coatings and roofing, among other
things — to increase their durability, insulation and
weathering protection.

Given this history, Kakoulli and her colleagues weren't expecting
to find asbestos on the walls of Enkleistra of St. Neophytos.
They initially set out to see if there was any change in the
materials used to create the monastery's numerous
wall paintings over time.

"We wanted to see how the technological part of making these
paintings follows or reveals anything of what we see in their
iconography and style," Kakoulli said.

The researchers analyzed some of the paintings on site using
various techniques, including infrared, ultraviolet and X-ray
fluorescence imaging. They also collected micro-samples of the
paintings and further analyzed their molecular and elemental
makeup with powerful
scanning electron microscopes and other methods.

A surprising find

One of the paintings they inspected depicted the "Enthroned
Christ" holding a book with a red frame. When they analyzed the
red frame, they found an asbestos-rich layer that was applied as
a finish coating between a red paint layer and a plaster layer
made up mostly of plant fibers. "So far, we've only found it in
relation to those red pigments," Kakoulli said.

Interestingly, the main deposits of asbestos in Cyprus come from
a high-elevation area approximately 38 miles (60 km) from the
monastery, which is near the coast. This location suggests the
monks may have been involved in a kind of interregional trade for
the asbestos.

The discovery raises many questions, such as why the asbestos was
used in this context (and only for the red frame in the
painting). It's also curious why the fibrous material apparently
wasn't used again in coatings until the 19th century. [ Image
Gallery: Stunning Byzantine Mosaic ]

The scientists are now searching for answers. They plan to return
to Cyprus to characterize more of the paintings at Enkleistra of
St. Neophytos. Kakoulli also hopes to revisit other wall
paintings she's previously studied in Cyprus, to see if they also
contained asbestos.

"I have a feeling that it's something that can be easily missed,"
Kakoulli said. "This was quite an accidental discovery."